Multicontact connectors have been widely used by the electrical and communication industry to interconnect circuit paths of component electrical circuits to form a larger composite electrical circuit. When component circuits are interconnected by connectors the composite circuit may fail to operate either from a failure of one of the component circuits or from a poor connection between connector contact terminals used to interconnect the paths of the circuits. The latter type of circuit failure quite often results from a poor connection or no connection at all between mating connector contact terminals. This type of connector failure may arise either because some particular matter or film formation has appeared on the contact terminal surfaces of the connectors so that the contact terminals may fail to make electrical connection with one and another.
Often times during the manufacture of connectors a contamination film inadvertently appears on ones of the contact terminals of connectors. Subsequently, the connectors are installed in and on electrical equipment to provide a means to interconnect component circuits that may be installed after the electrical equipment has been shipped and located on customer premises. When the component circuits are later installed, the contamination film results in a poor electrical connection between mating connector contact terminals that cause failure of the composite circuit. Locating these types of circuit failures is extremely difficult.
Measurement techniques and apparatus as evidenced by U.S. Pat. Nos. 3,735,254 and 3,974,443 have been developed to measure the electrical resistance of conducting surfaces. These measurement techniques, sometimes referred to as a so-called four-point contact resistance measurement, are accomplished by applying a known constant current to two outer points of a conducting surface area and measuring the voltage between two inner points of the same surface area. The electrical resistance of the conducting surface may then be readily ascertained from the known current and measured voltage. A problem with the apparatus used to make a four-point contact resistance measurement is that sufficient space must be available in order to gain access to the measurement points.
Apparatus has been disclosed by U.S. Pat. No. 3,996,514 for use with connectors to measure the resistance between printed circuit patterns on a circuit board and the connector contact terminals. The prior art connector measuring apparatus comprises a first pair of probes for engaging a conductor finger on the circuit board and a second pair of probes for engaging the contact terminal of the connector. Measurement of the resistance between the connector contact terminal and the circuit board conductor finger is made by applying a known constant current between one of the first and second probes and determining the voltage between the other ones of the first and second probes. A problem with this type of apparatus is that it is not intended for use in measuring contamination of a connector contact terminal and two pairs of probes are required to measure the contact resistance between a connector contact terminal and a circuit board conductor. A further problem occurs in that the apparatus as intended for use with circuit board edge connectors and is too bulky and cumbersome for use in measuring and detecting contamination on a contact terminal of a male pin insertion type of connector.
Accordingly, a need exists in the art for apparatus arranged for use in detecting and measuring contamination of a connector contact terminal. A need also exists for connector testing apparatus arranged for use in detecting and measuring contamination films and foreign material that inadvertently occur on contact terminals during manufacture of a pin insertion type of connector.